scholarly journals Role of Root and Stem Base Fungi in Fraxinus angustifolia (Vahl) Dieback in Croatian Floodplain Forests

Forests ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 607
Author(s):  
Jelena Kranjec Orlović ◽  
Maja Moro ◽  
Danko Diminić
Keyword(s):  
Large Scale ◽  
Internal Transcribed Spacer Region ◽  
Trichoderma Spp ◽  
Tree Health ◽  
Ash Dieback ◽  
Tree Stability ◽  
Hymenoscyphus Fraxineus ◽  
Crown Defoliation ◽  
Fraxinus Angustifolia

Large-scale ash (Fraxinus spp.) dieback caused by the fungus Hymenoscyphus fraxineus has been a major concern throughout Europe for more than two decades. Most of the related research has been focused on Fraxinus excelsior L., and there is still little information on fungal involvement in the dieback of Fraxinus angustifolia Vahl, especially in roots and stem bases, which play an important role in decline progress and tree stability. The objectives of this study were to identify fungi present in visually healthy and symptomatic wood tissues in basal parts of narrow-leaved ash trees in different decline phases, in order to determine the possible role of these fungi and their importance in the dieback process. The stem bases and roots of 90 trees in three different health categories, determined based on crown defoliation, were sampled in natural stands affected by ash dieback. Isolated fungal cultures were identified based on the rDNA ITS (Internal transcribed spacer) region and their association with tree health status was analyzed. In total, 68 different fungal taxa were confirmed, including Hymenoscyphus fraxineus and Armillaria spp., which were mainly present in roots, although overall in lower frequencies than on common ash in other studies. Most frequently isolated fungal taxa, which encompassed 51% of all obtained isolates, were Trichoderma spp., Ilyonectria robusta, Fusarium solani, Cladosporium cladosporioides, and Diaporthe cotoneastri. Their associations with tree health categories and presence in both symptomatic and visually healthy wood indicate that they act as opportunistic pathogens and early colonizers of weakened ash tissues. Research also revealed that, although the extent of crown defoliation and presence of root and stem necroses were associated, basal symptoms occurred on a number of trees with healthy looking crowns, meaning they can develop independently.

scholarly journals Phenotypic variability of Fraxinus excelsior L. and Fraxinus angustifolia Vahl under the ash dieback disease in the Czech Republic

2018 ◽  
Vol 64 (No. 6) ◽  
pp. 279-288
Author(s):  
Papić Slavica ◽  
Buriánek Václav ◽  
Longauer Roman ◽  
Kudláček Tomáš ◽  
Rozsypálek Jiří
Keyword(s):  
Phenotypic Variability ◽  
Fraxinus Excelsior ◽  
Ash Dieback ◽  
Hymenoscyphus Fraxineus ◽  
Forest Reproductive Material ◽  
Natural Range ◽  
Fraxinus Angustifolia ◽  
Reproductive Material ◽  
Dieback Disease

The study was carried out in the experiment with 16 provenances of common ash (Fraxinus excelsior Linnaeus) and 2 provenances of narrow-leaved ash (Fraxinus angustifolia Vahl) at a series of 5 parallel trial plots established in a gradient from lowland riverine to upland ravine sites. The role of the site, ash species and the provenance of common ash proved to have significant effects on the intensity of ash dieback (ADB) associated with the infection by Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz & Hosoya at the age of 20 years. Narrow-leaved ash was healthier, surviving and growing better than common ash on the trials situated inside as well as beyond its natural range. The ADB intensity was lower in the medium altitude and more easterly located trial plots with a more continental climate. The provenance of forest reproductive material proved to have a significant effect on the ADB damage and survival rate as well as the growth of ash across the trial plots of the experiment.

First report of Diplodia fraxini and Diplodia subglobosa causing canker and dieback of Fraxinus excelsior in Slovenia

Plant Disease ◽  
2021 ◽  
Author(s):  
Benedetto T. Linaldeddu ◽  
Carlo Bregant ◽  
Lucio Montecchio ◽  
Ana Brglez ◽  
Barbara Piškur ◽  
...  
Keyword(s):  
Sequence Data ◽  
Fungal Species ◽  
Pathogenicity Test ◽  
Limited Information ◽  
Internal Transcribed Spacer Region ◽  
Ash Dieback ◽  
Fungal Isolation ◽  
Hymenoscyphus Fraxineus ◽  
Botryosphaeriaceae Species ◽  
European Ash

Over the last decades the vitality and productivity of European ash trees in Slovenia has been seriously impacted by the onset of canker and dieback disease symptoms on young and old trees, primarily identified as ash dieback caused by Hymenoscyphus fraxineus. Given the limited information available about the aetiology of this emerging disease, a study was carried out to isolate, identify and characterize the fungal species involved in the observed ash symptoms. Field surveys were conducted in five forest sites where 50 symptomatic branch samples were collected. All samples were inspected and used for fungal isolation. Based on morphology, colony appearance and DNA sequence data of the internal transcribed spacer region (ITS), 125 fungal colonies belonging to five species were isolated and identified. Only a few symptomatic ash samples yielded colonies of H. fraxineus, whereas Botryosphaeriaceae species were isolated with a high frequency, with Diplodia fraxini as the dominant species. A pathogenicity test proved that all isolated species were pathogenic on European ash, causing bark lesions and wood discoloration. All Botryosphaeriaceae species isolated in this study are reported for the first time on European ash in Slovenia.

scholarly journals Decline of Fraxinus excelsior L. in parks of Saint Petersburg: Who is to blame – Hymenoscyphus fraxineus or Diplodia spp.?

2020 ◽  
Vol 73 (1) ◽  
pp. 43-51
Author(s):  
Dmitrii A. Shabunin ◽  
Andrey V. Selikhovkin ◽  
Elena Yu. Varentsova ◽  
Dmitry L. Musolin
Keyword(s):  
Light Microscopy ◽  
Fraxinus Excelsior ◽  
Ash Dieback ◽  
Saint Petersburg ◽  
Hymenoscyphus Fraxineus ◽  
Ash Trees ◽  
Fallen Leaves ◽  
European Ash

Abstract The weakening and decline of European ash Fraxinus excelsior L. and other ash species have been recorded at different locations in the suburbs of Saint Petersburg, Russia. During the summer of 2019 and spring of 2020, samples from leaves, petioles, and shoots were collected from the weakened and declining ash trees in three parks in Pushkin and Gatchina and maintained in humid chambers to induce the fructification of fungi. In total, 30 taxa of micromycetes belonging to 23 genera were identified using methods of light microscopy. Hymenoscyphus fraxineus, a putative agent of ash dieback, was not recorded in the samples collected in the crowns of trees, but only on the petioles of the fallen leaves in spring. Out of all the micromycetes recorded, only coelomycetes from the genus Diplodia Fr. (in particular, D. mutila) can damage the branches of ash trees and, thus, be considered pathogenic. It is likely that H. fraxineus opens “the entry of infection” and Diplodia spp. cause the major weakening and decline of branches. The data obtained can significantly change our understanding of the causes of ash dieback and possible methods of ash stand preservation. The reason for the low pathogenicity and activity of H. fraxineus, as well as the possible role of ascomycetes Diplodia spp. in the dieback of ash stands requires further research.

scholarly journals Gljivama slični organizmi u tlu odumirućih sastojina poljskog jasena (Fraxinus angustifolia Vahl)

2017 ◽  
Vol 141 (3-4) ◽  
pp. 122-122 ◽  
Author(s):  
Jelena Kranjec ◽  
Danko Diminić ◽  
Marija Hegol ◽  
Marno Milotić
Keyword(s):  
Pathogenic Fungus ◽  
Phytophthora Species ◽  
Soil Samples ◽  
Internal Transcribed Spacers ◽  
Biotic Factor ◽  
Ash Dieback ◽  
Important Species ◽  
Soil Extracts ◽  
Hymenoscyphus Fraxineus ◽  
Fraxinus Angustifolia

Narrow-leaved ash (Fraxinus angustifolia Vahl), ecologically and economically very important species of Croatian lowland forests, has been showing more prominent symptoms of dieback in the past few years. Research conducted so far has confirmed presence of the pathogenic fungus Hymenoscyphus fraxineus Baral, Queloz & Hosoya in the crowns and stems of the trees showing the symptoms of dieback at several locations in Croatia (Diminić 2015, Milotić et al. 2016). Since forest dieback is usually a consequence of multiple abiotic and biotic factors, research to find causes often encompass not just the above-ground parts of stands, but also the root systems and soil, where fungal-like organisms such as Phytophthora species are considered to be an important biotic factor responsible for tree mortality. The goal of this research was to detect fungal-like organisms in the soil of declining narrow-leaved ash stands in order to confirm or reject the hypothesis that pathogenic Phytophthora species have a potential role in the dieback and also to expand the knowledge about fungal-like organisms' diversity in Croatian forest soils. Total of 30 soil samples were collected from three forest management units (ten from each) in declining narrow-leaved ash stands, around the stems of trees of different health status according to Jankowiak et al. (2014). Fungal-like organisms were isolated using the soil baiting method according to Themann and Werres (1999), with Rhododendron catawbiense Michx. and Prunus laurocerasus L. leaves used as baits. Pure mycelia cultures showing vegetative morphological features characteristic for fungal-like organisms were obtained from 24 soil samples. To confirm this, sporangia production was induced in these isolates by flooding agar discs taken from 4-7 days old colonies with three different non-sterile soil extracts for each (1%, 1,5%, 5%). Sporangia were successfully induced in all isolates except one, which was chosen for the species identification using molecular methods together with five others (two isolates from each location). Genomic DNA was isolated using modified phenol-chloroform method according to Allemann et al. (1999). Amplification of internal transcribed spacers (ITS1 and ITS2) and 5.8 subunit of nuclear ITS rDNA region was conducted using the ITS4/ITS6 primer set, with reaction mixture and PCR protocol as in Grünwald et al. (2011). Amplification, PCR product purification and sequencing were conducted at InovaGen Ltd. (Zagreb, Croatia). All three isolates obtained from soil sampled around declining trees were identified as Phytopythium citrinum (B. Paul) Abad, De Cock, Bala, Robideau, Lodhi & Lévesque, and other three obtained from soil sampled around healthy trees were identified as Pythium lutarium Ali-Shtayeh, Pythium anandrum Drechsler and Phytopythium litorale Nechw. Presence of Phytophthora species in the soil of declining narrow-leaved ash stands wasn’t confirmed at the investigated locations, excluding them as one of the potential causative agents of narrow-leaved ash dieback in Croatia until further research is conducted. Although the Pythium and Phytopythium species were often isolated from the soil of declining forest stands and are known pathogens of seedling in forest nurseries, their possible role in dieback of narrow-leaved ash has yet to be determined.

scholarly journals Fungi isolated from shoots showing ash dieback in the Wolica Nature Reserve in Poland and artificially inoculated seedlings with Hymenoscyphus fraxineus

2019 ◽  
Vol 61 (1) ◽  
pp. 42-50 ◽  
Author(s):  
Anna Żółciak ◽  
Justyna Anna Nowakowska ◽  
Artur Pacia ◽  
Nenad Keča ◽  
Tomasz Oszako
Keyword(s):  
Nature Reserve ◽  
Pathogenic Fungus ◽  
Internal Transcribed Spacer Region ◽  
Ash Dieback ◽  
Hymenoscyphus Fraxineus ◽  
Ash Trees ◽  
Serious Disease ◽  
One Year ◽  
In The Beginning ◽  
Qualitative Changes

Abstract Ash dieback caused by an alien, invasive fungus Hymenoscyphus fraxineus is a serious disease of European ash species in many parts in Europe. In Poland, the disease was recorded in the beginning of the 1990s. This study was performed in 2016–2017 with the aim to identify fungi isolated from ash shoots showing dieback symptoms in the Wolica Nature Reserve in Poland, as well as from shoots of two years-old ash seedlings inoculated with H. fraxineus in the greenhouse. The most frequently isolated fungi from shoots of common ash (associated with the pathogenic fungus H. fraxineus) were identified on the basis of sequencing of the internal transcribed spacer region (ITS1) of fungal rDNA. In total, 19 fungal taxa were identified for ash shoots as follows: H. fraxineus, Fusarium avenaceum, Alternaria spp., Phomopsis oblonga, Diplodia mutila and other Phomopsis spp. The pathogen H. fraxineus was not found for all the shoots samples; one year after inoculation the aforementioned fungi and other species as: Alternaria alternata, Bionectria ochroleuca, Epicoccum nigrum, F. acuminatum, F. avenaceum, and Paraphaesphaeria neglecta were identified in inoculation point, as well as H. fraxineus. The same quantitative and qualitative changes of organisms were observed in the case of artificially colonised ash seedlings in the greenhouse, as well as in the shoots of adult ash trees in the forest.

scholarly journals European-wide forest monitoring substantiate the neccessity for a joint conservation strategy to rescue European ash species (Fraxinus spp.)

2021 ◽  
Author(s):  
Jan-Peter George ◽  
Tanja GM Sanders ◽  
Volkmar Timmermann ◽  
Nenad Potocic ◽  
Mait Lang
Keyword(s):  
Population Decline ◽  
Forest Monitoring ◽  
Conservation Strategy ◽  
Disease Spread ◽  
Ash Dieback ◽  
North East ◽  
Extreme Precipitation Events ◽  
Hymenoscyphus Fraxineus ◽  
Crown Defoliation ◽  
European Ash

European ash (Fraxinus excelsior) and narrow-leafed ash (F. angustifolia) are keystone forest tree species in Europe with a broad ecological amplitude and significant economic importance. Besides global warming both species are currently under significant thread by an invasive fungal pathogen that has been progressively spreading throughout the continent for almost three decades. Ash dieback caused by the invasive ascomycete Hymenoscyphus fraxineus is capable of damaging ash trees of all age classes and often leads to the ultimate death of a tree after years of progressively developing crown defoliation. While studies at national and regional level already suggested rapid decline of ash populations as a result of ash dieback, a comprehensive survey at European level with harmonized crown assessment data across countries could shed more light into the population decline from a pan-European perspective and could also pave the way for a new conservation strategy beyond national boarders. Here, we present data from the ICP Forests Level I crown condition monitoring including 27 countries, covering the timespan from 1987-2020. In total, 407 survey plots randomly distributed across these countries were analyzed resulting in >36,000 individual observations. We found a substantial increase in defoliation and mortality over time indicating that crown defoliation has almost doubled during the last three decades. Hotspots of mortality are currently situated in southern Scandinavia and north-eastern Europe, well corresponding to the fact that the disease spread fast from north-east to north-west. Overall survival probability after nearly 30 years of infection has already reached a critical value of 0.51, but with large differences among regions (0.00-0.907). Both a Cox proportional hazard model as well as an Aalen additive regression model strongly suggest that survival of ash is significantly lower in locations with excessive water regime and which experienced more extreme precipitation events during the last two decades. Our results underpin the necessity for fast governmental acting and joint rescue efforts beyond national boarders since overall mean defoliation will likely reach 50% as early as 2030 as suggested by time series forecasting . We strongly recommend to develop a pan-European conservation strategy before the decline will reach its tipping point resulting into non-reversible loss of diversity in the European forest landscape.

scholarly journals Mycobiome of Fraxinus excelsior With Different Phenotypic Susceptibility to Ash Dieback

2021 ◽  
Vol 4 ◽  
Author(s):  
Marta Agostinelli ◽  
Diem Nguyen ◽  
Johanna Witzell ◽  
Michelle Cleary
Keyword(s):  
Large Scale ◽  
Population Decline ◽  
Keystone Species ◽  
Fungal Species ◽  
Fraxinus Excelsior ◽  
Fungal Communities ◽  
Ash Dieback ◽  
Hymenoscyphus Fraxineus ◽  
Ash Trees ◽  
European Ash

For the last two decades, large-scale population decline of European ash (Fraxinus excelsior) has occurred in Europe because of the introduction of the alien fungal pathogen, Hymenoscyphus fraxineus, from East Asia. Since European ash is a keystone species having critical importance for biodiversity, and only a small percentage of the ash population appears to show some tolerance against the pathogen, the loss of ash trees means that other associated organisms, especially those with high or obligate associations to ash, are at risk of further species declines. In this study, we used high throughput DNA sequencing and multivariate analysis to characterize: (i) the mycobiome in aerial tissues (i.e., leaf, bark, and xylem) of ash trees showing different phenotypic response to ash dieback, (ii) the temporal variation in fungal communities across the growing season, and (iii) the similarity in fungal community structure between ash and other common trees species that may serve as an ecological niche substitute for ash microfungi. Results showed that fungal communities differed among the three tissue types, susceptibility classes, in time and between sites. Trophic analysis of functional groups using the FUNGuild tool indicated a higher presence of pathotrophic fungi in leaves than in bark and xylem. The share of pathotrophic fungi increased along a gradient of low to high disease susceptibility in both bark and xylem tissue, while the proportion of symbiotrophic fungi correspondingly decreased in both tissue types. Neighboring, alternative host trees did not share all the fungal species found in ash, however, most microfungi uniquely associated to ash in this study are generalists and not strictly host specific. The progressive disappearance of ash trees on the landscape imposes a high risk for extinction of Red-listed macrofungal species, and breeding for resistance against ash dieback should help sustain important biodiversity associated to ash. Microfungal diversity though may be less prone to such demise since most ash-associated endophytes appear to occur on a broad range of host species.

scholarly journals Survival of European Ash Seedlings Treated with Phosphite after Infection with the Hymenoscyphus fraxineus and Phytophthora Species

Forests ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 442 ◽  
Author(s):  
Nenad Keča ◽  
Milosz Tkaczyk ◽  
Anna Żółciak ◽  
Marcin Stocki ◽  
Hazem Kalaji ◽  
...  
Keyword(s):  
Large Scale ◽  
Phytophthora Species ◽  
Ash Dieback ◽  
European Continent ◽  
Individual Level ◽  
Hymenoscyphus Fraxineus ◽  
Species Mixture ◽  
Ash Trees ◽  
Decline Disease ◽  
The Individual

The European Fraxinus species are threatened by the alien invasive pathogen Hymenoscyphus fraxineus, which was introduced into Poland in the 1990s and has spread throughout the European continent, causing a large-scale decline of ash. There are no effective treatments to protect ash trees against ash dieback, which is caused by this pathogen, showing high variations in susceptibility at the individual level. Earlier studies have shown that the application of phosphites could improve the health of treated seedlings after artificial inoculation with H. fraxineus. Three-year-old F. excelsior seedlings were inoculated with the following pathogens: a H. fraxineus, Phytophthora species mixture (P. plurivora, P. megasperma, and P. taxon hungarica), in combination with two pathogens and mock-inoculated as the control, and then either watered or treated with ammonium phosphite (Actifos). Results showed significant differences in the survival of seedlings and symptoms of disease development among the treatments. Chlorophyll-a fluorescence parameters indicated a decrease in photosynthetic efficiency in infected plants, suggesting that they were under strong biotic stress, but none of the parameters could be used as a reliable bioindicator for ash decline disease. The application of Actifos enhanced the production of triterpenes (ursolic and oleanolic acid), and decreased the production of phenols (tyrosol) and sterols (β-sitosterol) in seedlings infected with H. fraxineus. Treatment with Actifos caused seedlings to enhance their response to pathogen(s) attack and increase their survival probability.

The Role of Sense of Direction and Other Factors During Navigation in a Large-Scale, Unconstrained Environment

2013 ◽  
Author(s):  
Elisabeth J. Ploran ◽  
Ericka Rovira ◽  
James C. Thompson ◽  
Raja Parasuraman
Keyword(s):  
Large Scale ◽  
Sense Of Direction
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